In recent times, there has been a shift from the use of macroswitches to microswitches in electronic goods and automobiles. The following is an explanation of the manufacturing technology of switches using a buckling phenomenon and the manufacturing technology of microswitches used for measuring acceleration.
Among switches using the buckling phenomenon, U.S. Pat. No. 5,010,219 is a push-button switch used in computers, etc., and is designed for the convenience of a user by limiting excessive buckling This switch is different from the present invention, which will be explained hereinafter, as it is a macroswitch, but similar as it uses a buckling phenomenon.
An invention related to the manufacture of a microswitch is Japanese patent number 2-260333. This invention grows a direct epitaxial layer on a silicon substrate, overcomes difficulties of growing an epitaxial layer on a P.+-. silicon layer, and utilizes thin-film technology to manufacture the microswitch. In these respects, this invention is similar to the present invention.
There are two types of research into threshold switches which are able to adjust voltage and acceleration. One is Japanese patent number 3-74022 realized by using a spring and mass. Here, centrifugal force of mass operates on a spring by acceleration. Another involves micro threshold switches by C. Robinson (Transducers '87) involving microscale cantilever-beam acceleration switches. Here, cantilever springs, each having different masses, contact different cantilever electrodes according to changes in acceleration such that a switching operation is performed.
However, with regard to the above former invention, as it is difficult to precisely manufacture the structural elements, even in identical products, not only does thresholdness for electrode contact create speed variation, but after manufacturing, threshold acceleration peculiar to each switch can change or it can be difficult to adjust. Further, in the above latter invention, as it operates in accordance to predetermined conditions, when a range of threshold acceleration and threshold acceleration section are not successive, a plurality of switch arrays must be formed such that a size of the product is enlarged. Therefore, a mistake made in design in the manufacturing process is often difficult to correct.